(Note: Extended Search Active) message for custom field

Dear experts,

In the transaction BBP_POC (Display PO) from extended search when we come back to simple search , if any of standard field eg account etc is having value , a message (Note : Extended Search Active) is displayed.

we have added 3 more fields to this screen and if these fields are not initial while coming to simple search we are not getting this message. How can we activate this for custom fields.